Tankards For the Memory

Nora Shekrie led her brother and his wife through the front door of her favorite public house, the back room of the Sub Standard. She deposited Nelson and Sharon in the front booth and went up to the bar to order Horrid Hoagies and Lugar Lager for lunch. As she waited for the waiter to appear, the grizzled sexagenarian two stools away started into what sounded like a typical sailor's tall tale.

"Almost died that night, I did. Should have, by rights. We were about 50 miles off the Alaskan coast. I won't mention her name, but she's one of the Exxon supertankers -- enough bad news about them already. It was wintertime; water woulda been frozen except for the salt in it -- y'know sea water don't freeze like reg'lar, don'cha?
"Well, 'bout two in the A.M., I was doin' my work on the port stern, when somethin' jostled a little, don't know what. Lost my footing on the deck, went over the side, and the ship just kept glidin' past me. Thought I was dead, right there, no life jacket, nothin' but the usual work clothes. Started treadin' water, and prayed harder 'n ever in my life, which hadn't been much up 'til then. Just watched her go, knew that shoutin' wouldn't do no good, not in the wind and over them motors.
"Mebbe a minute later, mebbe two, I see some lights, red 'n' green, where they shouldn't oughta be, wrong places on the ship. I figgered right on that: someone had saw me, lettin' me know not to give up. I started a-swimmin', and they turned that ship around. Got to me, threw out a line, I tied it around me, an' my mates hauled me up to th'olrop -- that's the lowest deck on the ship. Medic said a minute or two more, and I'd'a been a goner."
He leaned back and finished his beer. He looked around at the handful of listeners. "Anyone want to hear about the marlin I hauled in fishing in Puget Sound? Talkin's thirsty work."

Nora raised her hand. "You old salt, you tell a good tale. A lie that good deserves reward. I can't stay to listen, but the next round's on me." She signaled the bartender to refill the sailor's glass and add it to her tab.

What gave him away?

Hint

Answer

Survival time in the water, before hypothermia sets in, is highly dependent on water temperature. At freezing (zero centigrade, implied by his tale), a relatively still person has perhaps 15 minutes before losing consciousness; a moving person will get exhausted sooner. Survival time is about 45 minutes, but that assumes that the searchers can find you: a fully dressed body with no flotation device would slip beneath the surface and be lost.
The problem with finding him in time is that it takes about 20 minutes and 3 miles to bring a cruising supertanker to a stop; going in a circle takes a little longer, but would return the ship to his original position sooner. Either way, he wouldn't be able to swim and wouldn't be able to tie a line around himself when the ship reached him. The signal lights are a nice idea, but wouldn't change the fatal outcome.Hide